1. Field of the Invention
The present invention generally relates a device for monitoring tire air pressure of a vehicle. More specifically, the present invention relates a tire air pressure monitoring device that registers the ID code of a transmitter, and a receiver for use therewith.
2. Background Information
Japanese Published Patent Application No. 11-78445 discloses a tire air pressure monitoring device that uses pressure sensors to detect the air pressure of each tire on a vehicle. A transmitter is installed on each of the wheels to wirelessly transmit the air pressure data detected and an identification (ID) code to a receiver mounted on the vehicle. An alarm is issued in response to any abnormal tire air pressure data received. This tire air pressure monitoring device registers the ID codes transmitted from the transmitters with the receiver when the vehicle departs, after the wheels are rotated, and after the transmitters are changed. This allows the above mentioned tire air pressure monitoring device to distinguish between which of the four wheels of the vehicle the air pressure data belongs, and to distinguish between data belonging to the vehicle in question and that belonging to another vehicle.
In related technology, three types of data are transmitted from the transmitters of tire air pressure monitoring device, i.e., function codes, ID codes, and air pressure data. There are several types of function codes, two of which are transmitted during ID code registration. The first type of function code is sometimes called a normal code that is transmitted when a run switch on a standard transmitter is placed into the ON position. When the speed of the vehicle increases above a specified level, the run switch moves to the ON position due to centrifugal force, and the transmitter starts to transmit data. The second type of function code is sometimes called a registration code that replaces the normal code only when an ID code registration device is employed and an ID code is registered. In other words, the registration code is transmitted when the run switch is in the OFF position and when the ID code registration device is in use.
However, during ID code registration, data used for ID code registration is not identified by these function codes. The ID codes are separate identification codes provided by the transmitters for distinguishing between which of the air pressure data belongs to which of the four wheels of the vehicle. The ID codes are also used to distinguish between data belonging to the vehicle in question and that belonging to another vehicle. An air pressure sensor provides the air pressure data.
There are two methods of ID code registration. The first method uses the ID code registration device to register the ID codes when the vehicle is stationary. Specifically, the receiver is first switched to an ID code registration mode. Then, the ID code registration device is operated and gives instructions to the transmitters. The transmitters add the registration code, the ID codes and the air pressure data to the data format that is normally transmitted at high frequency, and then convert the data format to low frequency data for wirelessly transmitting it. When the ID code registration device receives this low frequency data from the transmitters, the ID code registration device transmits the data to the receiver over a wire to register the ID codes provided by the transmitters. In this way, even if data from another vehicle is received, misregistration of the ID code can be avoided because the data from the other vehicle is not converted into a low frequency.
The second method registers the ID code while the vehicle is moving, but without using the ID code registration device. Specifically, the receiver is first switched to the ID code registration mode, after the vehicle is operated above a specified level. By operating the vehicle, the receiver receives the ID codes provided by the data transmitted from the transmitters, and ID code registration takes place.
In view of the above, there exists a need for an improved tire air pressure monitoring device that is configured to be inexpensively constructed, and avoid misregistering ID codes from other vehicles. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
In the tire air pressure monitoring device discussed above, the first ID code registration method can avoid misregistering the ID code of another vehicle. However, it has been discovered that the first ID code registration method is typically costly and difficult to construct because the ID code registration device and the receiver are hard wired together. In the second ID code registration method, when the vehicle in question approaches another vehicle, it receives data transmitted from the other vehicle, the ID code from the other vehicle is misregistered, and thus the air pressure of the tires on the vehicle in question cannot be accurately determined.
It is an object of the present invention to address the problems found in the prior art, and thus provide a tire air pressure monitoring device and a receiver used therewith which is inexpensively and simply constructed.
It is a further object of the present invention to provide a tire air pressure monitoring device and a receiver used therewith which can avoid misregistering the ID codes from another vehicle regardless of the registration method employed.
In order to solve the above-mentioned problems, a tire air pressure monitoring device is provide which comprises a receiving component, an ID code registration determining component, a function code setting component and an ID code registration component. The receiving component is configured to wirelessly receive a detected function code, an ID code, and tire air pressure data for each wheel of a vehicle. The ID code registration determining component is configured to determine an ID code registration method based on a rotational state of the wheels. The function code setting component is configured to set a reference function code based on the ID code registration method determined by the ID code registration determining component when the reference function code corresponds to the detected function code of the receiving component. The ID code registration component is configured to register the ID codes of the wheels based on the reference function code set by the function code setting component.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.